/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.jmx;

import java.lang.reflect.Constructor;
import org.apache.log4j.Logger;
import org.apache.log4j.Level;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.spi.OptionHandler;

import java.util.Vector;
import java.util.Hashtable;
import java.lang.reflect.Method;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanConstructorInfo;
import javax.management.MBeanNotificationInfo;
import javax.management.MBeanInfo;
import javax.management.Attribute;

import javax.management.MBeanException;
import javax.management.AttributeNotFoundException;
import javax.management.RuntimeOperationsException;
import javax.management.ReflectionException;
import javax.management.InvalidAttributeValueException;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanParameterInfo;

import java.beans.Introspector;
import java.beans.BeanInfo;
import java.beans.PropertyDescriptor;
import java.beans.IntrospectionException;

public class LayoutDynamicMBean extends AbstractDynamicMBean {

	private MBeanConstructorInfo[] dConstructors = new MBeanConstructorInfo[1];
	private Vector dAttributes = new Vector();
	private String dClassName = this.getClass().getName();

	private Hashtable dynamicProps = new Hashtable(5);
	private MBeanOperationInfo[] dOperations = new MBeanOperationInfo[1];
	private String dDescription = "This MBean acts as a management facade for log4j layouts.";

	// This category instance is for logging.
	private static Logger cat = Logger.getLogger(LayoutDynamicMBean.class);

	// We wrap this layout instance.
	private Layout layout;

	public LayoutDynamicMBean(Layout layout) throws IntrospectionException {
		this.layout = layout;
		buildDynamicMBeanInfo();
	}

	private void buildDynamicMBeanInfo() throws IntrospectionException {
		Constructor[] constructors = this.getClass().getConstructors();
		dConstructors[0] = new MBeanConstructorInfo(
				"LayoutDynamicMBean(): Constructs a LayoutDynamicMBean instance",
				constructors[0]);

		BeanInfo bi = Introspector.getBeanInfo(layout.getClass());
		PropertyDescriptor[] pd = bi.getPropertyDescriptors();

		int size = pd.length;

		for (int i = 0; i < size; i++) {
			String name = pd[i].getName();
			Method readMethod = pd[i].getReadMethod();
			Method writeMethod = pd[i].getWriteMethod();
			if (readMethod != null) {
				Class returnClass = readMethod.getReturnType();
				if (isSupportedType(returnClass)) {
					String returnClassName;
					if (returnClass.isAssignableFrom(Level.class)) {
						returnClassName = "java.lang.String";
					} else {
						returnClassName = returnClass.getName();
					}

					dAttributes.add(new MBeanAttributeInfo(name,
							returnClassName, "Dynamic", true,
							writeMethod != null, false));
					dynamicProps.put(name, new MethodUnion(readMethod,
							writeMethod));
				}
			}
		}

		MBeanParameterInfo[] params = new MBeanParameterInfo[0];

		dOperations[0] = new MBeanOperationInfo("activateOptions",
				"activateOptions(): add an layout", params, "void",
				MBeanOperationInfo.ACTION);
	}

	private boolean isSupportedType(Class clazz) {
		if (clazz.isPrimitive()) {
			return true;
		}

		if (clazz == String.class) {
			return true;
		}
		if (clazz.isAssignableFrom(Level.class)) {
			return true;
		}

		return false;
	}

	public MBeanInfo getMBeanInfo() {
		cat.debug("getMBeanInfo called.");

		MBeanAttributeInfo[] attribs = new MBeanAttributeInfo[dAttributes
				.size()];
		dAttributes.toArray(attribs);

		return new MBeanInfo(dClassName, dDescription, attribs, dConstructors,
				dOperations, new MBeanNotificationInfo[0]);
	}

	public Object invoke(String operationName, Object params[],
			String signature[]) throws MBeanException, ReflectionException {

		if (operationName.equals("activateOptions")
				&& layout instanceof OptionHandler) {
			OptionHandler oh = (OptionHandler) layout;
			oh.activateOptions();
			return "Options activated.";
		}
		return null;
	}

	protected Logger getLogger() {
		return cat;
	}

	public Object getAttribute(String attributeName)
			throws AttributeNotFoundException, MBeanException,
			ReflectionException {

		// Check attributeName is not null to avoid NullPointerException later
		// on
		if (attributeName == null) {
			throw new RuntimeOperationsException(new IllegalArgumentException(
					"Attribute name cannot be null"),
					"Cannot invoke a getter of " + dClassName
							+ " with null attribute name");
		}

		MethodUnion mu = (MethodUnion) dynamicProps.get(attributeName);

		cat.debug("----name=" + attributeName + ", mu=" + mu);

		if (mu != null && mu.readMethod != null) {
			try {
				return mu.readMethod.invoke(layout, null);
			} catch (Exception e) {
				return null;
			}
		}

		// If attributeName has not been recognized throw an
		// AttributeNotFoundException
		throw (new AttributeNotFoundException("Cannot find " + attributeName
				+ " attribute in " + dClassName));

	}

	public void setAttribute(Attribute attribute)
			throws AttributeNotFoundException, InvalidAttributeValueException,
			MBeanException, ReflectionException {

		// Check attribute is not null to avoid NullPointerException later on
		if (attribute == null) {
			throw new RuntimeOperationsException(new IllegalArgumentException(
					"Attribute cannot be null"), "Cannot invoke a setter of "
					+ dClassName + " with null attribute");
		}
		String name = attribute.getName();
		Object value = attribute.getValue();

		if (name == null) {
			throw new RuntimeOperationsException(new IllegalArgumentException(
					"Attribute name cannot be null"),
					"Cannot invoke the setter of " + dClassName
							+ " with null attribute name");
		}

		MethodUnion mu = (MethodUnion) dynamicProps.get(name);

		if (mu != null && mu.writeMethod != null) {
			Object[] o = new Object[1];

			Class[] params = mu.writeMethod.getParameterTypes();
			if (params[0] == org.apache.log4j.Priority.class) {
				value = OptionConverter.toLevel((String) value,
						(Level) getAttribute(name));
			}
			o[0] = value;

			try {
				mu.writeMethod.invoke(layout, o);

			} catch (Exception e) {
				cat.error("FIXME", e);
			}
		} else {
			throw (new AttributeNotFoundException("Attribute " + name
					+ " not found in " + this.getClass().getName()));
		}
	}
}
